Hydronic heating systems are well-known in the art. In a floor heating system, for example, it is known to utilize an entire floor surface to transmit a precise amount of energy necessary to heat a room by circulating warm water (or an appropriate heat transfer fluid) through plastic tubing within a floor structure that lies just below the surface. Such a floor heating system distributes heat through the floor without unsightly radiators, duct grilles or other obvious appliances. In such structures, it is known to provide a subflooring structure that incorporates aluminum sheet metal heat transfer plates that are grooved so that the plastic tubing rests within the grooves. Heating fluid, such as warm water, passes through the tubing, heating the sheet metal heat transfer plates and the heated transfer plates conduct heat from the system from the subflooring system into the floor above where it radiates into the space to be heated. Similar such systems are known for heating walls and ceilings, utilizing plastic tubing and aluminum sheet metal heat transfer plates. Radiant tubing grids and manifold layouts are installed to facilitate efficient heat transfer to the heated space.
Heretofore, copper tubing was the preferred tubing and heat transfer plates were designed for spacing and holding the copper tubing in place within the floor substructure. Current practice, however, is to use a synthetic material for the tubing, such as polyethylene or polybutylene, herein called "plastic" tubing. Plastic tubing exhibits different characteristics than copper tubing and the current practice, based on adaptations from copper tubing systems, does not fully utilize the full value of a plastic tubing and aluminum heat transfer plate system.